Balancer set.



No. 881,636. PATENTED MAR. 10, 1908.

L. E. UNDBRWOOD & R. W. DOUGLASS.

BALANGER SET.

APPLICATION IiLBD OUT. 1, 1904.

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Richard .Douql'ass wool) and RIonAnD W., DOUGLASS, citizens This invention relates to systems of electween the two main conductors and the neuthe neutral wire is connected to a point bei only. sufiicient current to overcome the fric- .for the. counter-electromotive force then generator supplying current to the oven machine connected to the leg having the allied therewith whereby an increasedfieximatures connected inlseries and to the confwire, three-Wire type in which compensating systems the armatures of the two compensat- UNITED sTATEs TENT OFFICE.

LOUISE. UNDERWOOD AND RICHARD W. DOUGLASS, OF LYNN, MASSACHUSETTS, ASSIGNORS TO GENERAL ELECTRIC COMPANY,

A CORPORATION OF NEW YORK BALANCER SET.

Application filed October 1,

To all whom it concern: I

Be it known that we, LOUIS UNDER- of the United States, residing at Lynn, in the collnty of Essex and State of Massachusetts,

have invented certain new and useful IInrovementsin Balancer Sets, oifwhich the Qllowing is a specification.

trical-distribution of the well known twomachines are used to balance the load betral wire of the three-wire circuit. 'In such ing machines are ordinarily connected in se-. rles between the two mam conductors and tween the two armatures.

The machines are direct connected and en the system is perfectly balanced both machines run as motors taking from the line tion andoth'er losses of the machines. If, however, the'threewwire system becomes un balanced because of the increase in load between either of the'main conductors and the neutral wire, thereby lowering the voltage on that leg of, the system, the machine connected across that leg no longer runs as a motor,

equals or exceeds the im ressed electromesystem. Wlilll a still further overoading the compensating machine will operate as a loaded leg of the system, being driven by the light load. So much of the system herein described is old and well known and the novelty of the present invention residesin the arrangement of the exciting fields and parts bility of the system is secured, together with ease of adjustment and other' advantages which will be more specifically pointed out in the description and the annexed claims.

In the drawing, 1 and 2 represent the two distributing mains of the system su lied by power from an suitable source. The compensating mac ines 3 .and 4 have their arductors 1 and 2. The neutral wire5.is con-' nected'to the conductor 7 which joins the Specification of Letters Patent.

.portions of this resistance. fihe s Patented March 10, 1908.

1904. Serial N0. 226,750.

two armatures 3 and 4 and. includes a switch 6 by which this connection may be interrupted. Seriesfields 8 and 9 are provided for armatures 3 and 4 and may be shunted by German silver or other suitable resistances 10 and 11. it should be understood, however, that this invention is not confined to a system using compound. generators, but is equally applicable to systems using shunt wound. machines. The armatures 3 and 4 may be direct connected in any convenient manner as by being mounted on the same shaft, though for convenience of illustration we have shown them connected by the belt 12. The double-pole switch 13 serves to connect the two armatures to the distributing mains and one of the arinatures leads is provided with the starting box 14 of ordinary and gives the machines full field, the second step completes the armature circuit through the resistance and subsequent steps out out 15 and 16 are connected in-series between the outside armature leads thereby receiving the full voltage of the distributing mains when the circuit is completed through switch 13 and starting box 14. The fields 15 and -16 are provided respectively with the field rheostats 1.7 and 18 and a conductor 19 connects the neutral wire: of the dirt'ributing'system to the field circuit at a point located'between the two field rheostats.

The operation of the apparatus is as follows: With the switch 6 and the starting rheostat 14 open, the double-pole switch 13 is closed, after which the field circuit is completed through the starting rheostat 14- and the two machines are brought up to speed in the usual manner. After the machines have attained approximately normal speed the switch 6 ma be closed thereby connecting the center 0 the field circuit with the conductor 7 between the two armatures. The necessity of providing a switch 6 arises from the fact that otherwise only one machine will build up, the'other machine being. demagnetized owingto the passage of current through the armature instead "of through the shuntfield before the armature has attained sufiicient speed to produce an effective counter-electromotive force. I

It will be seenthat if the switch 6- is closed stat 17.

before the machines arestartcd there will be I several paths for the return to the line of cur when the armature .circuit is completed in rheostat 14, and the machines begin to re volve, practically all the "torque will be fur-' nished by armature 3 and the other machine will not build up a shunt field at all. If then the rheostat 14 is brought to a position in which all the resistance is cut out, armature 3 will be subjected. to substantially double its normal voltage and the system will be otherwise unbalanced as will readily appear to a person skilled in the art.

While we have shown the switch 6 as connected directly in the neutral wire it is obvious that it would also be efi'ective if located at 6 in the conductor 19. After the machines have once attained normal speed and the switch 6 has been closed, the field rheostats 17 and 18-inay be adjusted at will thus independently varying their respective fields 15 and 16, and so providing a ready means for independently varying the voltages of the two machines as circumstances may require. As each shunt field and its rlieostat is subjected to only the voltage between one of the distributing mains and the neutral wire, or in other Words to the normal voltage of the armature, standard shunt field windings may be used and the rheostats may be ,of low resistance, thus providing for the utilization of machinesof'standard type.

What we claim as ncwand desire to secure by Letters Patent of the United States, is,

i. In an electrical system, the combination of distributing mains, compensating machines joined by a conductor and connected across said mains, a mechanical connection between said machines, a shunt field for each machine, and means for connecting said shunt fields to said conductor joining said machines or fordisconnecting said fields therefrom. i

2. In an electrical system, the combination of distributing mains, compensating machines connected across said'mains t'o'a neutral conductor and driven b ener *y received from said mains, a inec ianica connection between said machines, shunt fields for said machines normally connected between said distributing mains and said neutral conductor, regulating means in circuit with said shunt fields, and means for preventing abnormal potential acrosssaid fields during starting.

3 In an electrical system, the combination of distributing mains, compensating machines oined by a conductor and connected across said mains, a mechanical connection between said machines, shunt fields for said machines, regulating means in each shunt field, and means for connecting said fields to the conductor joining said machines and for disconnecting said fields therefrom.

4. In an electrical system, the combination of distributing mains, compensating machines connected across said mams and to a heut-ral conductor, shunt fields connected between said distributing mains and said neutral conductor, and a switch in said neu: tral conductor between said machines and said shunt field connection.

5. In an electrical system, the combination of distributing mains of a three-wire circuit connected to a source of supply, comensating machines driven by energy derived From said mains and normally connected across said mains to the neutral conductor of said three-wire circuit, a shunt field for each machine, regulating means in each shunt field, means for connecting said shunt fields to said neutral conductor, and means for opening a connection between said fields andsaid armatures during the interval of startacross said mains and to a neutral conductor,

a field for one of said machines normally connected in shunt with its armature through a switch which can be opened during the operation of starting, and a field for the other of said machines. i

7. In an electrical system, the combination of distributing mains, compensating machines having armatures connected across said mains and to a neutral conductor, a shunt field for each of said machines normally connected in shunt with its armature through a switch which can be opened during the starting to prevent abnormal voltage on one of said shunt fields.

8. In an electrical system, a three-wire consumption circuit, compensating machines having their armatures connected inseries our hands this 28th day of Se iteinber, 1904.

LOUIS E. UNI) TRWOOD. RICHARD W. DOUGLASS. Witnesses JOHN A. McMANUs, J12, Duo/in) 0K. MCKILLoP. 

